Simple console countdown utility

counter.c

/*
 * counter.c - Simple console countdown utility
 * Copyright (c) 2014 Arkadiusz Bokowy
 *
 * This projected is licensed under the terms of the MIT license.
 *
 * Compilation:
 * gcc -Wall -Wextra -o counter counter.c
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <getopt.h>
#include <time.h>


/* Print formated output to the stdout. */
static void printtimer(time_t current, time_t start, int verbose) {

	unsigned int time_h, time_m, time_s;

	time_h = current / 3600;
	time_m = (current - time_h * 3600) / 60;
	time_s = current - time_h * 3600 - time_m * 60;

	if (!verbose)
		printf("\rETA: %u:%02u:%02u\r", time_h, time_m, time_s);
	else {
		unsigned int etime_h, etime_m, etime_s;
		etime_h = (start - current) / 3600;
		etime_m = (start - current - etime_h * 3600) / 60;
		etime_s = start - current - etime_h * 3600 - etime_m * 60;

		printf("\rETA: %u:%02u:%02u (elapsed: %u:%02u:%02u)\r",
				time_h, time_m, time_s, etime_h, etime_m, etime_s);
	}

	fflush(stdout);
}

int main(int argc, char *argv[]) {

	int opt;

	int beep = 0;
	int verbose = 0;
	char *command = NULL;

	while ((opt = getopt(argc, argv, "hbvc:")) != -1)
		switch (opt) {
		case 'h':
return_usage:
			printf("usage: %s [options] [[hh:]mm:]ss\n"
					"  -v\t\tprint more verbose output\n"
					"  -b\t\tplay beep sound on time out\n"
					"  -c CMD\trun given command on exit\n",
					argv[0]);
			return EXIT_SUCCESS;
		case 'b':
			beep = 1;
			break;
		case 'v':
			verbose = 1;
			break;
		case 'c':
			command = optarg;
			break;
		default:
			printf("Try `%s -h` for more informations.\n", argv[0]);
			return EXIT_FAILURE;
		}

	/* it should be only one argument (time) */
	if (optind + 1 != argc)
		goto return_usage;

	/* try to parse time argument */
	unsigned int time_h, time_m, time_s;
	if (sscanf(argv[optind], "%u:%u:%u", &time_h, &time_m, &time_s) != 3) {
		time_h = 0;
		if (sscanf(argv[optind], "%u:%u", &time_m, &time_s) != 2) {
			time_m = 0;
			if (sscanf(argv[optind], "%u", &time_s) != 1) {
				printf("error: unable to parse time\n");
				return EXIT_FAILURE;
			}
		}
	}

	/* convert given time to seconds */
	time_t input_time, counter;
	input_time = time_s + time_m * 60 + time_h * 3600;
	counter = input_time;

	/* count-down loop */
	printtimer(counter, input_time, verbose);
	while (counter--) {
		usleep(1000000);

		printtimer(counter, input_time, verbose);

		/* play beep sound on last 3 seconds */
		if (beep && counter < 4)
			printf("\a");
	}
	printf("\n");

	/* play quick 3 beeps on exit */
	if (beep) {
		int i = 3;
		while (i--) {
			usleep(100000);
			printf("\a");
		}
	}

	if (command)
		/* run given command on exit */
		return system(command);

	return EXIT_SUCCESS;
}